1. Field of the Invention
The present invention generally relates to a heating, ventilating and air conditioning unit (HVAC) adapted for mounting at the rear of a bus or similar type vehicle for transporting a large number of occupants. More specifically, the HVAC unit is self-contained, compactly arranged, and provided with an integrated heat pump. It is specially constructed for use with electric buses or electric/hybrid buses but can also be used with buses powered by internal combustion engines.
2. Description of the Prior Art
Heating and air conditioning units have been installed in various types of vehicles with the design and operating parameters of the HVAC units adapted for installation in specific types of vehicles. Passenger buses present particular problems due to the relatively large heating and cooling load produced by a plurality of passengers and extensive window areas. Also, it is difficult to obtain effective air circulation through a large volume of internal space to be heated or cooled. In prior art developments, passenger buses have been provided with HVAC units mounted on the roof or at other locations with the compressor assembly being driven from the engine which powers the bus. A condenser, condenser fan, evaporator and evaporator fan are associated with a compressor, expansion valve and other conventional components to provide a refrigeration system to supply conditioned air to the interior of the bus. Separate heating systems are usually provided for use when heated air is required to maintain the interior of the bus at a comfortable temperature level during periods of cold weather.
The following U.S. patents relate to the heating and cooling of a vehicle interior and the occupants therein:
The above listed patents disclose various roof and rear mounted air conditioning and heating units for buses and other vehicles. However, the above listed patents do not disclose a self-contained HVAC unit including a heat pump to provide a unitary climate control system utilizing a modular concept by which the heating and cooling capacity of the system may be varied depending upon the requirements of each installation without altering the size parameters of the supporting framework including a horizontally disposed support base and an upright support structure rigidly mounted on the base.
The self-contained electrical heat pump HVAC unit of this invention is mounted at the rear of a bus or other similar type vehicle in an area above the prime mover of the vehicle which is usually vacant and available. The mounting of the HVAC unit in this area of the bus enables installation without alteration of the roof or other external configuration of the bus.
The HVAC unit is preferably modular in design and includes a supporting framework on which is mounted and supported a condenser or condensers including a fan or fans, an evaporator or evaporators, an evaporator blower or blowers, a compressor or compressors, an air plenum assembly or air plenum assemblies and refrigeration and heat pump system components to provide a complete refrigeration and heat pump cycle. The supporting framework includes an upright support structure attached to a support base and panels are provided to enclose, protect the heat exchangers and isolate the condenser or condensers from the evaporator or evaporators to maintain proper air flow. The bus may be provided with a ducted or free blowing air circulation system or a combination of both depending upon the installation requirements for each individual bus. When in a cooling mode, the air circulation system in the bus is associated with the evaporator or evaporators and evaporator blowers. The condensers and condenser fans are associated with air inlet panels at the sides of the bus and an air outlet panel at the rear of the bus. When in a heating mode, the association of the components is switched with the condensers or condenser becoming evaporators and the evaporator or evaporators becoming condensers in a manner well known in the operation of a heat pump.
The rear mounted, multi-functional climate control system with integrated heat pump of this invention is especially designed for electric or electric/hybrid urban buses. However, it is also fully capable of being incorporated into a conventional bus utilizing an internal combustion engine as the prime mover. The construction of this system does not require the formation of holes or other alterations to the roof of the bus to accommodate the condenser and enables the integration of a heat pump system into the unit and eliminates the possibility of snow or ice clogging the condenser. The modular concept of the system simplifies the design and eases installation of the system by virtue of enabling different system capacities to be installed in the same available space by varying the number of compressors, condensers, evaporators and associated fans in the available space thereby minimizing energy consumption by adapting the capabilities of the HVAC unit with the requirements of the installation.
It is therefore an object of the present invention to provide a self-contained HVAC unit with integrated electric heat pump mounted at the rear of a bus or other similar vehicle with the components being mounted on a supporting framework capable of fitting into the normally available space above the bus internal combustion engine or power unit in an electric or electric/hybrid bus. The supporting framework or structure is capable of supporting different capacity HVAC components in the same available space thereby enabling the capacity of the HVAC unit to satisfy the heating and cooling requirement of each particular installation without altering the overall size of the unit.
Another object of this invention is to provide a self-contained unitary HVAC unit in which the supporting framework includes a supporting base and a centrally located upright support structure with a condenser or condensers mounted on the support base against one side of the upright support structure and an evaporator or evaporators mounted on the other side of the support structure with the evaporator assembly located forwardly of the condenser assembly. The evaporator assembly includes a blower or blowers and the condenser assembly includes a fan or fans for air circulation through the evaporator and condenser assemblies by circulating air through and over the coil and fin evaporator and condenser assemblies. The supporting framework also supports one or more electrically driven compressors and the other conventional components of a HVAC unit, such as an expansion valve, accumulator, dryer, fans, refrigerant circulating tubing and other components to form a closed refrigeration/heat pump system.
A further object of the invention is to provide a self contained modular HVAC unit in which the support structure includes panels to isolate the condenser and evaporator assemblies, an air plenum or plenums associated with the evaporator or evaporators for circulation of conditioned air into the passenger area of the bus by utilizing a blower or blowers and a ducted air circulation system, a free blowing air circulation system or a combination of both systems.
Yet another object of this invention is to provide a HVAC in accordance with the preceding objects and which will conform to conventional forms of manufacture, be of simple construction and easy to use so as to provide a device that will be economically feasible, long lasting and relatively trouble free in operation.